The present invention relates to counter countermeasure systems and more particularly to improved techniques for determining the range and direction of an interference source.
One of the most common techniques for disrupting a tracking radar system is to provide a noise jammer to produce interference at the frequency of the tracking radar to prevent information retrieval from the radar signal. This technique is particularly effective when the radar frequency is known or can be approximated because of conditions or environment which dictate the use of specific radar frequencies. While such jamming techniques can in some instances be substantially overcome by using different frequencies or sophisticated cancelling equipment, it is sometimes desirable to be able to simultaneously locate the position of the jammer to enable jammer destruction or provide information as to enemy position and deployment.
One such prior method for determining jammer position has utilized a special directional auxiliary antenna mounted to the main radar antenna of a tracking radar. A special loop is then used to determine signal phase as the radar tracks the jammer, which together with the pointing angles of the antennas, allows a jammer position determination. This technique requires the special directional auxiliary antenna and is limited in accuracy by the distance restriction fixed by mounting the directional antenna onto the radar antenna. In addition, a special loop is required to develope the phase signal necessary for position determination.
Other prior known techniques have used the conventional triangulation approach where the electromagnetic interference radiation is detected by several directional detectors located at various stations or in multiple vehicles separated by relatively large distances. By knowing the distance between the stations or the vehicles and the direction of the jammer from each position, the range and therefore position of the jammer, can easily be calculated. While this technique is relatively successful, the distance between stations must be precisely known and continuously monitored, and the direction information must be transmitted between stations. Such conditions require constant information exchange between plural stations, particularly for moving vehicles, and subject the stations to enemy detection that might otherwise be concealed.
Accordingly, the present invention has been developed to overcome the specific shortcomings of the above known and similar techniques and to provide a relatively simple and reliable technique for determining range and azimuth of an interference source.